1. Field of the Invention
The present invention relates to an integrated backlight driving chip and related LED backlight device, and more particularly, to an integrated backlight driving chip in which a scaler having digital control capability is integrated, and a related LED backlight device.
2. Description of the Prior Art
A liquid crystal display (LCD) offers the advantages of thin construction, low power consumption, and low radiation, so that the LCD is widely applied in various electronic products, such as LCD televisions, computer systems, mobile phones, and personal digital assistants. The LCD operates by varying voltage drops between opposite sides of a liquid crystal layer for twisting liquid crystal molecules in the liquid crystal layer to alter transmittance of the liquid crystal layer, which can be controlled to produce images with the aid of light provided by a backlight module. A typical LCD device includes an LCD panel and a control chipset, a driving chipset, and a backlight module. The control chipset is responsible for transforming and processing image data. The driving chipset is utilized for outputting corresponding voltage signals to control the transmittance of each pixel on the LCD panel for displaying image data. In general, the control chipset usually includes a scaler chip for performing expansion or reduction process on the image data to generate the image data conforming to a required output standard, such as a required resolution or aspect ratio of vertical and horizontal lines.
Since liquid crystal does not emit light itself, the LCD device is usually equipped with a backlight module for providing required light sources to display the image data. Most traditional backlight modules use cold cathode fluorescent lamps (CCFLs) for light sources. In recent years, light emitting diodes (LEDs) used as light sources have become popular because of energy saving, long device lifetime, no mercury used, high achievable color gamut, no idle time, and fast response speed. Furthermore, as the luminous efficiency increases and the cost decreases, LEDs have gradually replaced CCFLs to be the light source in a backlight module.
Please refer to FIG. 1, which is a schematic diagram of an LED backlight device 10 according to the prior art. The LED backlight device 10 includes a backlight module 102, a backlight driving chip 104, and a backlight driving circuit board 106. As shown in FIG. 1, the backlight module 102 includes LED chains C1 to Cm arranged in parallel, where each LED chain includes at least one LED in series. The backlight driving chip 104 is disposed on the backlight driving circuit board 106 for driving the backlight module 102 and controlling the brightness of the LEDs. In general, for various application requirements, the backlight driving chip 104 is able to control current passing through each LED chain or switch frequency by using an external resistor R. However, the external resistor R cannot supply a wide range of capacitance values; therefore, different types of resistors are required for various application situations. In other words, the backlight driving chip 104 needs to operate incoordination with the external resistor R with various resistance values for various application requirements, resulting in high costs. In addition, a corresponding backlight driving chip 104 is required according to the backlight module 102 of different configurations, such as having various numbers of LEDs or various arrangements of the LED chain. Therefore, the conventional backlight driving chip cannot meet all requirements of current or switching frequency due to the existing limitations and is unable to provide flexible usage, causing inconvenience.
Regarding fault detection of the LED backlight device 10, operating power may be cut off when an over-voltage situation or an over-current situation occurs so that the LED backlight module 102 and the backlight driving chip 104 will stop operation accordingly for fault protection. Subsequently, the operating power may be turned on again for follow-up backlight driving operation. However, the fault situation is not able to be recorded meaning the fault situation may be difficult to resolve.